1. Field of the Invention
The invention relates to an automatic transmission provided with a power take-off mechanism for use in a variety of vehicles including a dump truck, a concrete or similar mixer vehicle, fire trucks, etc.
2. Description of the Related Art
A conventional automatic transmission provided with a power take-off mechanism has three frictional clutches which are axially disposed on a line with each other. Another conventional automatic transmission with a power take-off mechanism which has a power take-off drive gear on the outer side of a drum which houses a portion of a frictional clutch. In this transmission the power take-off drive gear is located on the conventional cylindrically formed clutch drum.
In a transmission having plural frictional clutches positioned axially of each other, an elongated axial space is required. When the vehicle has a sufficiently large space for the transmission, no problems are presented. However, when the vehicle has a RR (rear engine, rear drive) System, the vehicle has a reduced axial space and it is difficult to position the transmission into the reduced space. When the transmission is provided with a lock-up clutch mechanism, an even longer axial space is required and it is more difficult to accommodate the transmission in the vehicle.
As a solution of the problem, it has been considered to position the clutches coaxially and radially with respect to each other and, consequently, to axially shorten the space requirement. However, when the mechanism also includes a PTO drive gear on one of the clutch drums in the arrangement of the coaxially and radially positioned clutches, as discussed, the transmission casing is radially expanded or increased as result of the radially positioned clutches and the PTO drive gear.